Speech signals and audio signals have different characteristics. Therefore, speech codecs for speech signals and audio codecs for audio signals have been independently researched using unique characteristics of the speech signals and the audio signals. A currently widely used speech codec, for example, an Adaptive Multi-Rate Wideband Plus (AMR-WB+) codec has a Code Excitation Linear Prediction (CELP) structure, and may extract and quantize a speech parameter based on a Linear Predictive Coder (LPC) according to a speech model of a speech. A widely used audio codec, for example, a High-Efficiency Advanced Coding version 2 (HE-AAC V2) codec may optimally quantize a frequency coefficient in a psychological acoustic aspect by considering acoustic characteristics of human beings in a frequency domain.
Accordingly, there is a need for a technology that may effectively select an internal module according to a characteristic of an input signal to thereby effectively encode both a speech signal and a audio signal.